Screen-grate for ball-mills.



F. E. MARCY.

SCREENUGRATYE FOB BALL |VHLLS. APPLICATION FILED JUNI; 3. |914. IIENEwEDAPR. I9, I9I5.

u o o 5, r I

-mo 'E MII F. E. MARCY.

SCREEN GRATE Fon BALL MILLS.

APPLICATION FILED )UNE 3. 1914. RENEWED APR. 19, |9l5.

j Patented Sept. M,

3 SHEETS-sneu 2.

F. E. MARCY.

SCREEN GRATE FOR BML MILLS.

APPLICATION FILED IuIIE 3. 1914. IIENEwEo APR. .19. |915.

Patented Sept. 14, 1915.

3 SHEETS-SHEET 3.

FRANK E. MARCY, 01E'A SALT LAKE CITY, UTAH.'

SCREEN-GRATE FOR BALL-MILLS.

Specification of Letters Patent.

Patented sept. ia, i915.

application filed .rune 3, 1914', serial No. 842,722. Renewed aprn 19,1915. 'serial No. 22,488.

To all whom it may concern Be it known that I, FRANK E. MARCY, a citizenof the United States, residing at Salt Lake City, in the county of SaltLake and -State of Utah, have invented certainI new and usefulImprovements in Screen-Grates for Ball-Mills, of which the following isfull, clear, and exactV description, reference being had to theaccompanying drawlngs',

forming a part hereof.

My invention has relation to improvements in screen-grates for ballmills; and

` it consists in the novel features of construction more fully set forthin the specification and pointed out in the claims.

In lthe drawings, Figure 1 is an end elevation of a mill employing mygrate, viewed from the feed end, parts being broken away; Fig. 2 is aside elevation with parts insee-- tion;.Fig. 3 is an inner face view ofonehalf of the grate, only one of the grate sectors and sections thereofbeing detailed; Fig. 1 is a transverse section through one of thesectors on the line 4- -4 of Fig. 3;

Fig. 5 is a rear edge view of one 'of the grate sections; Fig. 6 isva-face view looking at the slotted or recessed side of the section;Fig. 7 is an enlarged cross-'section on the line 7-7 of Fig. 5; Fig. 8is an enlarged view on the order of Fig. 5,k showing however a portiononly, of the grate section; Figs. 9 and 10, and 11 and 12 arerespectively elevations and end views of the bolts for securing thegratesectors to the drum head; "Fig 13 is a'view o n the orderfof Fig. 3showinga'modified form of gratesector; Fig. 14 is an ledge view of oneof the I modified sectors; F ig.y 15 is a rear edge view of one of thesections entering into the construction of the sector; Fig. 116 is abottom plan of Fig. 15; Fig. 17'is a cross-.section on the line 172-17of Fig. 16; yand Fig. 18`

isA a sectional detail on Fig. 13.

The present' im rovement is directed to the construction o gratesformingthe diaphragm or transverse screens of ball-mills on the order ofthat described in my pending application for patent forv ball mills,

'the line 1 8-18 of VKSerial Number 788,132, filed September 4,

1913, whether or not the mill `be provided.

with radial screenssuch as shown in the structure of said pendingapplication.

The object of the invention is to provide a grate composedof a seriesofradial segments or sectors, each segment being in turn.

subdividedinto a series of transverse sections, be the latter arcuate orstraight, the said sections being so formed as to leave spaces orscreening interstices between them for the passage'of the materialcrushed in the crushing compartment of the mill.

A further 'object is to provide a grate of a detailed description of theinvention, which is as follows:

Referring to the drawings, and for the present to Figs. 1 to 12inclusive, 1, represents 'a cylindrical (preferably cast iron)equivalent tubular member) provided with a lining of.- silex, hardgravir-on, steel or equivalent layer 2, said lining being confined tothe `walls of the barrel and to thehead 3 ate-fthe intake end of thebarrel, the opposite head 4 not necessarily requiringa lining.` Theintake for the feed or lpulp is `through the hollow trunnion 5, saidfeedentering the crushing compartment C of the mill, the crushed material`or finished product discharging through the discharge trunnion 6.Forming one of the terminal walls of the crushing compartment, to wit,the Wall adjacent the discharge trunnion 6, andV spaced from the head 4by a series of radial vanes, blades or lifters 7 is` an annular ordisk-like screenor grate (or equivalent diaphragm)4 comprising a seriesof. radial primary segments or sectors 8 (of man` ganese steel), eachlsectorbeing 1n turn made up of a.ser1es of transverse sectlons separablealongplanes or surfaces disposed subcontainer, drum, or tumbling barrel'(or grate bearing against the inner edges of the lifte'rs 7 againstwhich it is firmly drawn by the bolts 9, 9 whose inner ends are securedto the grate, and Whose outer ends are passed through the head 4:,suitable nuts n serving to tighten the parts as clearly obvious from thedrawings.

The walls of the lcentral opening of the grate 8 are beveled andsurround and engage a central imperforate (except at the center) disk 10provided with a flaring hub 11 which directs the vfinished product(dropped by the lifters 7) into the trunnion 6, it being understood thatthe material passing through the grate enters the radial compartmentsbounded by the grate sectors 8 and disk l0, the head 4, and the lifters7, the grate sectors 8 and disk 10 being spaced from the head 4 adistance equal to the widths of the lifters or blades 7, against theedges of which they bear.

The central opening of the flaring hub 11 registers with thecorresponding opening of the disk 10 (Fig. 2) whereby a central or axialpassage is formed through these members establishing lcommunicationbetween the discharge trunnion 6 and the crushing compartment C, thuskeeping the mill from choking upi should the mill become overloaded,said axial passage allowing the ma- .terial to discharge from the millinto the trunnion 6 in the usual Way. As shown, the

peripheral surface of the hub 11 is substantially conical, but anyequivalent outwardly tapering (or inwardlyvflaring) member will answerthe purpose of directing,` ,the finished product dropped by the lifters7, into the trunnion 6. For example a pyramidal or equivalent hubsuitably formed would fall within my invention.

As stated at the outset, the invention herein is'directed particularlyto the construction of thescreening grate, the features above alluded tobeing with one or two exceptions well understood in the art, and notherein claimed. In the grate illustrated in the figures at presentconsidered, I provide an outer ring section 12 for each grate segment orsector, the cross-section of the ring being substantially as shown in `Fig. 4, that is, to say, the inner face of each ring section is providedwith a bevel groove l1, which receives the corresponding outer marginalcurved bevel edge t of the outer section tm, of a grate sector, thesector comprising in addition to the outer section m, an innerimperforate section m', and a series of intermediate transverse'sectionsm, ,the outer faces of theseveral sections (that is to say,

the faces turned toward thehead 4 of the i drum) being, provided' withperforated ears or lugs e which,'when' the sections are assembledregister along radial lines, and collectively form a rib through whichis passed a securing bolt 13 which'couplesthe several sections together.Thus the individu-al sections of any sector are joined by the bolts 13Ypassed through the registering perforations o of they ears e, thesector as such being in turn connected to the head 4 by the bolts 9, 9.The inner edges of the sections m are beveled (Fig. 4), said bevel edgesengaging the corresponding .bevel edges of the plate or disk 10, thelatter forming virtually an imperforate inner extension of the gratecomposed of the sectors 8. The ring sections 12 (locked to the gratesectors by the tongue and groove connection t, It, referred to) serve asfiller-in pieces between the grate sectors and the inner walls of thedrum. Formed along the inner face of each section m. (or the face whichengages the outer face of an adjacent section), and at points betweenand exterior to the ears c, are recesses or depressions cl the bases ofwhich are slightly inclined to the planes of the faces of the'sector,whereby there result grate openings or passages between the severalsections (m), the said openings flaring toward the discharge face of thegrate (Fig. 4f). The flare or taper of these openings however is soslight that with any wear of the inner face of the sector or thatexposed to the-material and grinding balls in the crushing compartment,no perceptible 4change or enlargement in the cross-section of thepassage is apparent, the finished product (after passing through thegrate) being Substantially uniform in size. The grate is constructed todeliver material crushed from one-sixteenth to one-eighth inch. In otherwords, where the feed is crushed downto 8 or 16 mesh the present grateis employed; where it is crushed finer, finishing screens are`used, asin myy pending application aforesaid, no claim being made herein howeverfor a combination of grate and screens.

It may be stated in passing that one of the objects herein is to reducethe amount of slime, which, as well known, is always difficult of properconcentration. The securing bolt 9 for the sector 8 passes through andbetween twoy of the sections m m. These particular sections arenecessarily provided with semicylindrical depressions 1' for the passageof the bolt therethrough, the head of the bolt being received by asocket s formed in the sections (Figs. 3, 5, 6). Any equivalent methodof giving the bolt ample purchase is however contemplated by myinvention. The number of blades or lifters 7 is equal to the number ofsectors 8, one blade supporting two sectors opposite the radial joint orseam between the sectors (Figs. l, 3). T he terminals of the ringsectionsl are beveled (Fig. 3) whereby the end of one` section overlapsthe meeting end of an adjacent section along a seam or joint .frinclined to a radial line lOO through the joint, the latter cuttingacross the edge of the blade 7 by which any two sectors 8 are supported.

In the form of grate above described, the

rable along curved or cylindrical surfaces,-

the openings in the grate being curved as compared with the straightopeningsor slots in the first form described. Thus in Figs. 13, 14, theouter sector section is represented b v the letter (t, the inner sectionby ft, and the slot-forming sections by a, the slots d' being curvedorarcuate. Like the first form described, the arcuate sections areprovided with perforated ears or lugs eon their outer faces traversed bya securing bolt 13. In addition however, the sections a are providedwith studs or projections 14 at the terminals and centers of their inneredges, which enter corresponding depressions or sockets 22 in the outeredge of an adjacent section and thus serve to lock the sectionscircularly. vIn mills where a special finishing screening and sizingcompartment C is rovided beyond the crushing compartment@ for handlingvery fine material or that crushed finer than one-sixteenth, as in mypending application aforesaid and in many existing mills, and where itis usual to provide buckets B for directing the material toward the axisof the mill and into the discharge trunnion 6, I may employ the bucketas an abutment to prevent circular displacement of the grate by castingon the side of the outer ring 12 a lug 15 which bears against thebuck-et. This arrangement dispenses with the requirement of the outerthrough bolt 9 as shown in the first form described. It is not howeverclaimed herein as it falls within the purview of the ordinary skilledmechanic. Except in the particulars noted the modified grate (Figs. 13to 18) is the saine as the first form described. It is apparent that thegrate is susceptible of other modifications without departing from thenature or spirit of my invention.

It will be seen from the foregoing that the danger of blinding thescreen is entirely eliminated, it being possible to keep the openings orslots (al, d',) clean at all times owing to the sectional character ofeach grate sector. lThe sectors may be enlarged or reduced radially (andhence circularly) to any cross-.sectional diameterof drum or mill. Theplanes of separationfbetween the sections m of any sector aresubstantially parallel to the axis of rotation of the drum, theseparating planes between corresponding sections of the entire series ofsectors forming the faces'of a prism; whereas the correspondingseparating surfacesbetween the sections c form the surface of acylinder. In either form however theseveral separating surfaces from theaxis of the drum to its periphery, whether prismatic or cylindrical, areconcentric with the rotation axis of the drum. While I have shown theseparating surfaces between corresponding sections of the severalsectors continuous around the axis of the drum, it would not falloutside the spirit of my invention if said surfaces were arranged instaggered relation. In fact, I do not wish to be restricted to thespecific details here shown, as theyV may be altered in many particularswithout affecting the nature of the invention. For example, the recessesor slots d, d, instead of being formed on the bottom side of any section(7a, a), that is to say, the side facing the axis of rotation of thedrum, may be on the upper side or on the side facing the outer walls ofthe drum. This reversal of the formations would obviously fall under myinvention. The details might be altered in other particulars notnecessary here to mention. bviously, the screen need not be limited inits application to ball-mills specifically; it might be used in otherconnections.

Features illustrated but not alluded to are well known in the art andrequire no description in the present connection.

Having described my invention, what I- Claim is z- 1. In combinationwith a drum rotatable about a fixed axis and provided with terminalheads having openings respectively for the feed and discharge'of thematerial, a series of radial blades or lifters disposed on the innersurface of one of the'heads, sectional grate sectors having radialmeeting edges resting on the inner edges ofthe blades, and means forsecuring the sections of the sectors together at points between theblades.`

2. Inl combination with a drum rotatable about a fixed axispfavndprovided with terminal heads having openings respectively for the feedand discharge of the material, a series of radial blades or liftersdisposed on the inner surface of one of the heads, radial grate sectorscomposed each of a series of sections disposed transversely to the radiiof the sector, and having meeting edges resting on the inner edges ofthe blades, and means traversing the sdbtors radially at points betweenthe blades for securing the sections to one another.

3. In combination with a cylindrical drum `rotatable about its axis, aseries of ci-rcularly disposed ring sections distributed along the innerwalls of the drum, a series of grate sectors forming an annular grateand dis- `posed transverse to the rotation axis of the drum. each sectorcomprising a series of seciat i iat tions separable along surfacestransverse to the vradii of the sector and provided with slot formationsadjacent said surfaces of separation, an outer terminal section for eachsector d ovetailing with a corresponding ring section, -an innerimperforate section forming the opposite end of each sector` a centraldisk engaging the inner sections of the respective sectors, and meansfor securing the parts fixedly in the drum.

'-t. Incombination with a drum rotatable about a fixed axis and providedwith terminal heads having openings respectively for the feed anddischarge of the material. a series of radial blades or lifters disposedon the inner surface of the discharge head, grate sectors having radialmeeting edges resting on the inner edges of the blades, and ringsections engaging the outer portions of the sectors, the ring sectionsforming a lap joint across the edge of the blade supporting the sectors,and means for securing the sectors to the head and into firm engagementwith the blades aforesaid.

5. In a grate, a sector composed of independent sections, the sectionshaving pro jections and corresponding depressions engaged by saidprojections to prevent displacement between the sections.

(l. In combination with a drinn rotatable about a lixed axis andprovided with terminal heads having openings respectively for the feedand discharge of the material. a series of radial blades or liftersdisposed on the inner surface of one of the heads, and grate sectorshaving radial meeting edges resting on the inner edges ot' the blades.

T. In combination with a drum rotatable about a fixed axis and providedwith terminal heads having openings respectivel)v for the feed anddischarge of the material, a series of radial blades or lifters disposedon the inner surface of the discharge head, grate sectors having radialmeeting edges resting on the inner edges of the blades, and means forsecuring the sectors to the head and into firm engagement with theblades aforesaid.

In testimony whereof I aiiix my signature, in presence of two witnesses.

FRANK E. MRCY.

IVitnesses H. I. GooDsPEED, A. L. HEADBERG.

Copies of this patent may be obtained Afor ve cents each, 'by addressingthe Commissioner of Patents,

Washington, D. C.

